1. Field of the Invention
The present invention relates to a Vuilleumier heat pump for use in air conditioning for refrigeration or heating and cooling.
2. Description of the Prior Art
FIG. 1 is a sectional view showing an arrangement of a conventional Vuilleumier heat pump which is disclosed in, for example, an article by H. Carlsen and N. E. Andersen entitled `Simulation Model for the Design of Vuilleumier Machines` in Advances in Heat Pumps: ASME Winter Annual Meeting (1989), pp. 39-46. In FIG. 1, reference numeral 1 means a hot cylinder, 2 means a hot displacer reciprocating inside the hot cylinder 1, 3 is a hot displacer rod coupled with the hot displacer 2, 4 is a hot displacer connecting rod coupled with the hot displacer rod 3, and 5 is a hot crank coupled with the hot displacer connecting rod 4. Further, reference numeral 6 means a cold cylinder, 7 is a cold displacer reciprocating inside the cold cylinder 6, 8 is a cold displacer rod coupled with the cold displacer 7, 9 is a cold displacer connecting rod coupled with the cold displacer rod 8, and 10 is a cold crank coupled with the cold displacer connecting rod 9. Reference numeral 11 means a coupling shaft for coupling the hot crank 5 with the cold crank 10 so as to enable motion of the hot displacer 2 and the cold displacer 7 with a phase difference of substantially a right angle therebetween.
Reference numeral 12 means a hot space which is defined between the hot cylinder 1 and an upper portion of the hot displacer 2, and 13 means a hot/moderate temperature space which is defined between the hot cylinder 1 and a lower portion of the hot displacer 2. Further, reference numeral 14 is a heater coupled with the hot space 12, 15 means a hot regenerator coupled with the heater 14, 16 is hot/moderate temperature heat exchanger for coupling the hot regenerator 15 with the hot/moderate temperature space 13, 17 is a cold space which is defined between the cold cylinder 6 and an upper portion of the cold displacer 7, and 18 is a cold/moderate temperature space which is defined between the cold cylinder 6 and a lower portion of the cold displacer 7. Reference numeral 19 means a cold heat exchanger coupled with the cold space 17, 20 means a cold regenerator coupled with the cold heat exchanger 19, 21 is a cold/moderate temperature heat exchanger for coupling the cold regenerator 20 with the cold/moderate temperature space 18, and 22 is a coupling pipe for communicating between the hot/moderate temperature space 13 and the cold/moderate temperature space 18. A working space is defined by the heater 14, the hot regenerator 15, the hot/moderate temperature heat exchanger 16, the cold heat exchanger 19, the cold regenerator 20, the cold/moderate temperature heat exchanger 21, an inside of the coupling pipe 22, the hot space 12, the hot/moderate temperature space 13, the cold space 17, the cold/moderate temperature space 18. A working gas such as helium is sealed in the working space.
Reference numeral 23 means a crank case involving the hot displacer connecting rod 4, the hot crank 5, the cold displacer connecting rod 9, the cold crank 10, and the coupling shaft 11. Reference numeral 24 means a buffer chamber in the crank case 23, and the hot displacer rod 3 and the cold displacer rod 8 move in and out of the buffer chamber 24. Reference numeral 25 means a hot displacer seal which is mounted on the hot displacer 2 so as not to directly mix the working gas in the hot space 12 with that in the hot/moderate temperature space 13. Reference numeral 26 means a hot displacer rod seal which prevents the working gas from leaking from the hot/moderate temperature space 13 to the buffer chamber 24. Reference numeral 27 means a cold displacer seal which is mounted on the cold displacer 7 so as not to directly mix the working gas in the cold space 17 with that in the cold/moderate temperature space 18. Reference numeral 28 means a cold displacer rod seal which prevents the working gas from leaking from the cold/moderate temperature space 18 to the buffer chamber 24.
A description will now be given of the operation.
When clockwise rotating the hot crank 5 and the cold crank 10 which are coupled with each other through the coupling shaft 11, the hot displacer 2 reciprocates in the hot cylinder 1, and the cold displacer 7 reciprocates in the cold cylinder 6. Further, the cold displacer 7 reciprocates with a delay of about a right angle.
The heater 14 is heated up typically between 400.degree. and 800.degree. C. by, for example, a burner (not shown), and on the other hand, the hot/moderate temperature heat exchanger 16 is cooled to a vicinity of room temperature by cooling water or the like. The reciprocation of the hot displacer 2 causes the internal working gas to alternate between the hot space 12 and the hot/moderate temperature space 13 by passing through the heater 14, the hot regenerator 15, and the hot/moderate temperature heat exchanger 16. At this time, a pressure fluctuation of the gas is generated in the working space due to variation of occupied ratio of the hot working gas and the moderate temperature working gas. FIG. 2 is a waveform diagram showing the reciprocation of the hot displacer 2 and the pressure fluctuation of the internal working gas in one cycle. The reciprocation of the cold displacer 7 is also shown in FIG. 2. In FIG. 2, the reciprocation of the hot displacer 2 is shown by the solid wavy line, the pressure fluctuation of the internal working gas is shown by the broken wavy line, and the reciprocation of the cold displacer 7 is shown by the one dot chain wavy line. The pressure fluctuation is transmitted to the working gas in the cold cylinder 6 through the coupling pipe 22. In this case, FIG. 3 shows a P-V diagram described in the hot space 12, FIG. 4 is a P-V diagram described in the cold space 17, FIG. 5 is a P-V diagram described in the hot/moderate temperature space 13, and FIG. 6 is a P-V diagram described in the cold/moderate temperature space 18. As understood from the above description, expansion work is generated in the hot space 12 and the cold space 17, and compression work is generated in the cold/moderate temperature space 18 and the hot/moderate temperature space 13.
The expansion work generated in the cold space 17 is drawn as cold from the cold heat exchanger 19, and the cold is used for cooling. The compression work generated in the cold/moderate temperature space 18 and the hot/moderate temperature space 13 is drawn as hot from the cold/moderate temperature heat exchanger 21 and the hot/moderate temperature heat exchanger 16, and the hot is used for heating.
The Vuilleumier heat pump is started by an electric motor (not shown) coupled with the hot crank 5 or the cold crank 10. The hot displacer rod 3 and the cold displacer rod 8 reciprocate with the phase difference of about a right angle as in the case of the hot displacer 2 and the cold displacer 7. Accordingly, the volume of the working space is varied so that the pressure fluctuation generated in the working space causes external work. Consequently, the work causes the Vuilleumier heat pump to be self-sustaining and operated at a working frequency balancing with sliding friction of the hot displacer seal 25, the hot displacer rod seal 26, the cold displacer seal 27, the cold displacer rod seal 28, or friction of each bearing slider.
The conventional Vuilleumier heat pump is provided as set forth hereinbefore. Hence, there are some drawbacks in that, for example, a driving mechanism is required which includes the hot displacer connecting rod 4, the hot crank 5, the cold displacer connecting rod 9, the cold crank 10, the coupling shaft 11 and the like so as to drive the hot displacer and the cold displacer, resulting in a large-sized driving mechanism, and a large-sized crank case 23 involving the driving mechanism.
Further, the hot displacer and the cold displacer are mechanically coupled with each other through the hot displacer connecting rod, the hot crank, the cold displacer connecting rod, the cold crank and the coupling shaft. Accordingly, there are other drawbacks in that, for example, an arrangement of the hot cylinder and the cold cylinder is restricted.